[Simh] Hardware fidelity in the VAX family simulators

[Ethan Dicks]

On Wed, Jul 8, 2015 at 8:10 PM, Johnny Billquist <bqt at softjar.se> wrote:
>>> I haven't found microcode sources or listings for the 750, 730,
>>> MicroVAX I, or 8600, for example.
>>
>>    FWIW, the 725/730 was somewhat unique in that the micro store was
>> entirely RAM.  All of the microcode was loaded by the CFE at power on and
>> none was in ROM.  Also, the 730 micro engine was based on industry standard
>> 29xx family bit slice parts.

Yep.

>>    So, if anyway if anybody does find the sources or development tools for
>> the 730/725 microcode, I'd love to see a copy.

I'd love to see it too, just to get an idea of what's really under the
hood there.

> The 11/750 had RAM to store patches to the microcode, but the basic version
> of the microcode was in ROM.

I remember having to keep the microcode patch TU58 installed at some
point after 1992 or so, because it would be slurped in when needed.
It's not like were moving data over that drive.

> Where did the 11/725 and 11/730 load their microcode from. Surely not the
> TU58...

Yep.  Takes about 20 minutes unless you optimize the files in order of
request... then it's about 5 minutes.

-ethan